Elucidation of the recognition mechanism of hydrophobic proteins by a glycochaperone

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H02843
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 37020:Chemistry and chemical methodology of biomolecules-related
• Research Institution: Suntory Foundation for Life Sciences
• Principal Investigator: Shimamoto Keiko 公益財団法人サントリー生命科学財団, 生物有機科学研究所・構造生命科学研究部, 特任研究員 (70235638)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 糖脂質 / 膜挿入 / シャペロン / 生体膜 / 糖鎖 / 疎水性相互作用

Outline of Final Research Achievements

A glycolipid named MPIase (membrane protein integrase), composed of a long sugar chain and pyrophospholipid, was proven essential for membrane protein integration in the inner membrane of Escherichia coli. We have reported that a synthesized minimal unit of MPIase possessing only one trisaccharide, mini-MPIase-3, involves an essential structure for the integration activity. In this study, to elucidate the mechanism of protein insertion using MPIase, we analyzed the molecular interactions between MPIase analogues and the model substrate, Pf3 coat protein, using physicochemical methods. Surface plasmon resonance (SPR) and saturation transfer difference nuclear magnetic resonance (STD-NMR) analyses revealed that the 6-O-acetyl group on glucosamine and pyrophosphate group of MPIase play important roles in the interaction with the hydrophobic region and basic amino acids of the substrate protein.

Free Research Field

生物有機化学

Academic Significance and Societal Importance of the Research Achievements

従来から知られている膜挿入因子は全てタンパク質であり、MPIaseは非タンパク質性の糖脂質がはたらく初めての例である。今回、我々はMPIaseの長い糖鎖部分が疎水性の高い基質タンパク質を素早く捕捉し凝集抑制することを実証した。MPIaseがタンパク質を捕捉する機構を調べることで、膜挿入機構の全容が明らかになるだけでなく、新しい機能をもった糖脂質を探索する手がかりになると考えられる。